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Review Article DOI: 10.18231/2394-4994.2018.0058

Anesthesia for (Part II)

Lalit Gupta1, Bhavna Gupta2,*

1Assistant Professor, 2Senior Resident, Dept. of Anaesthesia, Maulana Azad Medical College and Lok Nayak , New Delhi, India

*Corresponding Author: Email: [email protected]

Received: 9th February, 2018 Accepted: 12th February, 2018

Abstract The central (CNS) deserves special consideration in the perioperative setting for several reasons for an anesthetist. An understanding of is essential because neuro continues to develop and evolution of neurosurgical practice is accompanied by new challenges for the anesthetist. Basic knowledge and expertise of the neuro-anesthetist can directly influence outcome. With the recent advancement in functional and minimally invasive procedures, there is an increased emphasis on the provision of optimal operative conditions, preservation of neurocognitive function, minimizing interference with electrophysiological , and a rapid, high-quality recovery. So, during neuro anesthesia, anesthesiologist needs to know physiology of CNS including cerebral metabolism and cerebral blood flow. Neuro anesthesia can be challenging, because sometimes apparently contradictory demands must be managed, for example, achieving optimal conditions for neurophysiological monitoring while maintaining sufficient depth, or maintaining delivery to neuronal tissue and simultaneously preventing high blood pressures that might induce local . One of the peculiarities of neuro anesthesia has always been that as much importance is attached to wakening the patient as sending them to . We have included the anesthesia for neurosurgery in two parts. In the first part, we had discussed cerebral anatomy, physiology and intracranial pressure, in the second part we have included anesthesia considerations for for , aneurysmal surgery, temporal lobe surgery, trans sphenoidal surgery and traumatic brain .

Keywords: Anesthesia, Neurosurgery.

Introduction 10.18231/2394-4994.2018.0001), we had discussed The (CNS) deserves special cerebral anatomy, physiology and intracranial pressure, consideration in the perioperative setting for several in the current second part we have included anesthesia reasons for an anesthetist. An understanding of considerations for surgery for brain tumor, aneurysmal neuroanatomy is essential because neuro anesthesia surgery, temporal lobe surgery, trans sphenoidal surgery continues to develop and evolution of neurosurgical and . practice is accompanied by new challenges for the anesthetist.1 Basic knowledge and expertise of the neuro- Common Surgical Procedures anesthetist can directly influence patient outcome. With Neurosurgery is a complex surgery because every the recent advancement in functional and minimally part of the brain undergoing surgery needs some special invasive procedures, there is an increased emphasis on consideration apart from general principles of the provision of optimal operative conditions, management. preservation of neurocognitive function, minimizing Surgery for Brain Tumors1-3 (Table 1) interference with electrophysiological monitoring, and a 1. The fundamental anesthetic considerations in tumor rapid, high-quality recovery.2,3 So, during neuro surgery are proper positioning of the patient to anesthesia, anesthesiologist needs to know physiology of facilitate the surgical approach; providing adequate CNS including cerebral metabolism and cerebral blood relaxation of the brain to optimize surgical flow. Neuro anesthesia can be challenging, because conditions; and preventing well-known devastating sometimes apparently contradictory demands has to be complications, such as venous air . managed, for example, achieving optimal conditions for 2. Preoperative assessment of the level of neurophysiological monitoring while maintaining (, GCS) (Table- sufficient anesthetic depth, or maintaining oxygen 2) and a review of relevant radiologic studies should delivery to neuronal tissue and simultaneously be performed, and the results should be taken into preventing high blood pressures that might induce local consideration in the anesthetic plan. bleeding.2 One of the peculiarities of neuro anesthesia 3. Adequate brain relaxation is typically achieved with has always been that as much importance is attached to a standard anesthetic, including sub-MAC volatile wakening the patient as sending them to sleep. We have anesthesia, an infusion, mild to moderate reviewed the anesthesia for neurosurgery in two parts. In hyperventilation, and Mannitol. the first part (Anesthesia for Neurosurgery (Part I) (DOI:

Indian Journal of Clinical Anaesthesia, July-September, 2018;5(3):299-305 299 Lalit Gupta et al. Anesthesia for neurosurgery (Part II)

Table 1: Management strategies Protocol Management Strategy Preoperative 1. Note and record the GCS of patient 2. Avoid / if patient is drowsy or ICP is raised Positioning and Monitoring Sitting: 1. Standard ASA monitoring, CVP line and Precordial Doppler if possible( for VAE) 2. Prone / semi recombinant: 3. Standard ASA monitoring, Foley and if surgery demands. Intraoperative Induction: 1. Etomidate / Thiopentone or with under deep anaesthesia to avoid increase in ICP. 2. Maintainace: 3. Minimize ICP and maintain adequate CPP. 4. Opioid and/or volatile anesthetic ( is preferred) with or without nitrous . 5. Avoid intraoperative long acting muscle relaxants if motor function is tested. 6. Mannitol (0.25-1 g/kg IV) also can be given before opening of dura. 7. Maintain euvolemia and normocapnia if normal ICP; temporary hyperventilation for relaxing brain if required. tight Postoperative 1. Avoid coughing, straining during extubation by prior use of lignocaine or small dose of opioid. 2. Always note and Record postoperative GCS

Glasgow Coma Scale (GCS)4,5: GCS is a neurological professors of neurosurgery at the University of scale which aims to give a reliable and objective way of Glasgow's Institute of Neurological at the city's recording the conscious state of a person for initial as Southern General Hospital. It has following point scale well as subsequent assessment. The scale was published system: in 1974 by Graham Teasdale and Bryan J. Jennett,

Table 2: Glasgow coma scale 1 2 3 4 Eye (E) Opens eyes to Does not open Opens eyes to painful Opens eyes verbal eyes stimulus spontaneously commands Verbal(V) Makes Oriented Makes no Speaks Confused and incomprehensible and talks sound incoherent words disoriented sounds normally Motor(M) Abnormal Extension to painful flexion to painful Flexion / Localizes to Obeys No movement stimuli (decereberate stimuli Withdrawal to painful commands posture) (decorticate painful stimuli stimuli posture)

The GCS for intubated is scored out of 10 as the neurological signs and altered level of sensorium or verbal component falls away neck rigidity. Generally, brain injury is classified on the basis of 2. Surgical or endovascular intervention is required to GCS score (E+V+M) as: prevent hemorrhage in patients who survive 1. Severe, GCS < 8–9 (In trauma, a GCS of 8 or less hemorrhage to prevent further re-bleeding. indicates a need for endotracheal intubation) 3. Patients with Sub arachnoid hemorrhage due to 2. Moderate, GCS 9–12 are at risk of many complications which 3. Minor, GCS ≥ 13 include cardiac dysfunction, neurogenic pulmonary edema, as well as hemorrhage from Cerebral Aneurysm Surgery 2,6,7 (Table 3) the aneurysm. 1. The is the most common 4. Triple H is the modality of treatment of cause of . The most vasospasm. Triple H therapy includes common manifestation is sudden onset of severe hypervolumia, hypertension and hemodilution. , with and and focal Nimodipine, a type of calcium channel blockade

Indian Journal of Clinical Anaesthesia, July-September, 2018;5(3):299-305 300 Lalit Gupta et al. Anesthesia for neurosurgery (Part II)

decreases the overall morbidity and mortality risk Temporary clipping time should be less than 10 minutes from vasospasm. to avoid risk of ischemia. Effect of (32-25○ 5. The major causes of morbidity and mortality from C) is confounded by various factors which include grade SAH include rebleeding, ischemic cerebal injury, of SAH, time of clip application, neuroprotective agents, infarction and development of hydrocephalus and anesthetic agents, experience and intraoperative . repair of aneurysm.

Table 3 Protocol Management Strategy Preoperative 1. Note and record the GCS of patient 2. History of hypertension, CAD, DM 3. Patient is often on calcium channel blockers. 4. ECG changes may mimic with cardiac event (T-wave inversions, U waves, ST-segment depressions, prolonged QT interval, and rarely Q waves) 5. No (may raise PCO2) Positioning and 1. Supine: the best surgical exposure is related to specific head positions. The proper Monitoring angle of microscopic view may minimize neurovascular injury and brain retraction. 2. Standard ASA monitoring, and arterial line if surgery demands (HT/CAD). Intraoperative Induction: 1. Opioid plus propofol and/or volatile anesthetic. 2. Avoid increases in systemic (to prevent rebleeding). 3. Maintain cerebral perfusion pressure to avoid further ischemia (to prevent vasospasm). Maintenance 1. Maintain normal to increased systemic blood pressure to avoid ischemia during surgical retraction and temporary clipping. 2. Maintain normocapnia and avoid unnecessary hyperventilation. 3. Mannitol (0.25-1 g/kg IV) also can be given. Postoperative 1. Maintain slight head-up position or as required by . 2. Maintain normal to increased systemic blood pressure to prevent further vasospasm.(HHH therapy is given as needed) 3. Early awakening is recommended to facilitate neurologic assessment.

4. Anesthesia management includes perioperative Trans-sphenoidal Surgery 1,8,9 (Table 4) hemodynamic stability, maintenance of normal 1. Transphenoidal surgery is done for pituitary intracranial pressure, smooth surgical conditions adenoma. Anesthesia is challenging as it takes into such as lax brain, maintenance of adequate cerebral considerations of endocrine abnormalities blood flow, rapid recovery, and emergence at associated with process. Trans nasal Trans completion of surgery. sphenoidal (TTNS) excision has benefits in terms of 5. Gluco-corticois are supplemented in patients with recovery and reduced mortality. hypo-pituitarism on evening before surgery with 2. Pituitary tumors are more commonly associated 100 mg hydrocortisone, and is repeated just before with acromegaly, gigantism and Cushing disease. or at the beginning of surgery and third dose is given These patients have also associated diabetes on evening after the operation. mellitus, hypertension and obstructive sleep apnea. They also have airway abnormalities owing to presence of acromegaly. 3. Intra-operative anesthesia management is based on size of tumour and associated co-morbidities, and physiological disturbances. Dexmeditomidine and remifentanil are newer and excellent drugs used for maintenance of hemodynamic stability. Post- operative management includes strict monitoring, and looking for complications such as diabetes insipidus and CSF leak.

Indian Journal of Clinical Anaesthesia, July-September, 2018;5(3):299-305 301 Lalit Gupta et al. Anesthesia for neurosurgery (Part II)

Table 4 Protocol Management Strategy Preoperative 1. Cardiac abnormalities: LVH, CAD, , conduction disturbances, and CHF are commonly associated with hyper-secretion from pituitary, acromegaly and Cushing's disease. (The role of ECG and ECHO is of prime importance). 2. Possibilities of raised ICP and hydrocephalous. 3. and associated sleep apnea syndrome. 4. Visual field defects are common. 5. Significant incidence of DM and thyroid disorders. 6. Antihypertensive, antianginals, antiarrhythmics, antacids, etc. should be administered as per scheduled protocol on day of surgery. 7. No should be prescribed. Positioning and 1. Head up position: more risk of VAE. Monitoring 2. Standard ASA monitoring, plus arterial line, Large IV . Intraoperative Induction: 1. Large mask required, mask ventilation may be difficult. 2. Oral intubation, consider awake FOB if likely to be very difficult. Flexometallic tube plus throat pack. 3. Standard induction with Thiopentone / propofol with inhalation agents (MAC<1) is preferred. 4. Proper positioning (obese patient) to prevent pressure induced injury (esp. Ulnar nerve) Maintainance: 1. Balanced technique as used in neuro anaesthesia 2. Induced : MAP above 65 mmHg 3. Vigilance for complications 4. Disconnection 5. VAE 6. Dissection into cavernous sinus with haemorrhage 7. Pressure on face or eyes Postoperative Antiemetic 1. Emergence 2. Look for Clear blood or CSF from airway 3. Aim to minimize coughing Postoperative 1. Attention to complications 2. Diabetes insipidus (usually transient) 3. Pan Analgesia: Oral ± IM/ IV Nasal CPAP is contraindicated after TNTS surgery (risk of Tension Pneumothorax).

2. Some of the relative contraindications of this Awake (Temporal lobe surgery) 1,10,11,12 procedure include difficult airway, obstructed sleep (Table 5) apnea, or orthopnea. Patients who suffer from severe 1. refers to some intracranial anxiety, claustrophobia or other psychiatric neurosurgical procedures in which patients are disorders may be inappropriate to undergo awake sedated and free yet are able to respond to craniotomy verbal or visual commands. This is preferred to 3. Anesthesia approach depends on length of surgery, facilitate monitoring of regions of brain on which patient factors, surgeon and there is no consensus surgeon is operating. on the best approach for awake craniotomy.

Table 5 Protocol Management Strategy Preoperative 1. Detailed history is taken, especially taking in detail history of , nature of aura etc, and detailed medication history is also taken in account. 2. Investigation 1. Unilateral carotid of sodium amobarbital (a ). 2. Determines lateralization of speech, short term (establishes cerebral language and Memory representation of either hemisphere). Indian Journal of Clinical Anaesthesia, July-September, 2018;5(3):299-305 302 Lalit Gupta et al. Anesthesia for neurosurgery (Part II)

Videotelemetry 1. Continuous EEG with subdural, parenchymal or foramen ovale electrodes to localize focus of Seizures. : 1. agents avoided Positioning and Head up position: Monitoring 1. The patient position is dictated by the location of the lesion. This is usually a lateral or supine position, but with occipital lesions and testing the visual cortex, a sitting position may be used. 2. In any position, it is important that when the patient is fully awake during mapping that they are able to see and communicate with the anaesthetist or neuropsychologist. 3. Sterile drapes must not cover patients face (during .) Monitoring: 1. Routine ASA monitoring 2. Gas analysis to confirm airway patency (optional) 3. Continuous neurological assessment 4. (BIS) monitoring 5. Careful attention to patient comfort and warming Intraoperative Conscious Sedation Technique( “awake throughout”): 1. Propofol is one of the most frequently used drugs either alone or in combination with remifentanil. 2. Droperidol 2.5-7.5 mg plus a like 5-10µg/kg plus 0.25-0.5µg/kg/min, or 0.7 µg/kg plus 0.7µg/kg/h. 3. Dexmedetomidine may be the ideal sedative (minimal respiratory depression) for awake procedures (A loading dose of 0.5–1.0 µg/kg1 over 20 min is then followed by an infusion rate of 0.2–0.7 µg /kg/ h). “Asleep–Awake–Asleep” Technique. 1. This is often the preferred method for (general anesthesia for the initial craniotomy he anaesthetic drugs are either reduced or stopped and the airway device is removed, when the patient has regained upper airway reflexes and it is safe to do so. 2. Once resection of the lesion is complete, can be re-introduced and with re-insertion of the airway device). 3. The anesthetic drugs used for this technique are varied, but often are the same as those used in the ‘awake throughout’ technique. General anesthesia Reserved for children, patients with continuous movement disorders, and patients with an increased ICP. If provoking agent is required for seizures, methohexitone 0.3 mg/kg. For termination if necessary, thiopentone 1 mg/kg. Postoperative Antiemetic Postoperative attention to complications 1. Bleeding 2. Seizures 3. psychological disturbances Analgesia: Oral ± IM/ IV narcotics block at the site of insertion of Mayfield pins

3. Maintenance of cerebral blood flow has to be Anesthesia for Traumatic Brain Injury 3,15-18 (TBI) adequate to avoid cerebral ischemia, thereby 1. The term is interchangeable with minimizing secondary injury to brain. Hypotension, traumatic brain injury and brain injury and is hypoxia, raised ICP and should be avoided. defined as trauma to the head other than superficial 4. There is 10% incidence of unstable cervical spine injury with TBI. Risk factors include GCS score less 2. Maintenance of airway and breathing is of than 8 and motor accident. Thus manual in paramount significance in critical care setting and line stabilization should be maintained to avoid more importantly for patients with head injury as neurological damage brain is very sensitive to the effects of 5. Patients with TBI should be orally intubated because and hypercapnia of potential presence of basilar fracture, risk of which may be exacerbated with nasal intubation

Indian Journal of Clinical Anaesthesia, July-September, 2018;5(3):299-305 303 Lalit Gupta et al. Anesthesia for neurosurgery (Part II)

6. All intravenous induction agents except d. may be used as an adjunct to other cause a fall in CBF, CMRO2 and ICP. Etomidate therapy for controlling ICP. Barbiturate therapy is causes a little change in blood pressure despite appropriate only in patients who are reducing CMRO2 and may be advantageous but hemodynamically stable and have been adequately may lead to adrenal insufficiency leading to delayed resuscitated. Propofol is a reasonable alternative to hypotension barbiturates for ICP management. 7. Risk of aspiration during airway procedure should e. Current recommendations are that patients with TBI be minimized. Administration of should be maintained at normocapnia except when prevents coughing thereby preventing sudden hypocapnia is necessary to control acute increases in increase in ICP. Argument against succinyl choline ICP. is the potential to increase ICP, however the 11. Coagulation disorders are a common problem after suspected rise of ICP is only transient and may be TBI. Coagulation disorders can also result from blunted with adequate dose of induction agent such secondary brain injury. Hemostatic drugs such as as thiopentone antifibrinolytics, such as trenaxamic acid and 8. Hypotension is extremely detrimental to brain. Goal procoagulants such as recombinant factor VII are is to maintain SBP above 90 mmHg, CPP in range sometimes used in treatment of after of 50-70 mmHg. In absence of ICP monitoring an TBI. ICP of 20 mmHg should be assumed and MAP 12. Hyperglycemia after TBI is associated with should be kept above 60 mmHg. increased morbidity and mortality. Tight glucose 9. The optimal Hemoglobin level in TBI patients is control with intensive insulin therapy remains still unclear but there is no benefit of a liberal controversial due to recurring dangerous episodes of transfusion strategy (transfusion when Hb<10 g/dl) hypoglycemia. Evidence shows a target glucose in moderate to severe TBI patients and it is not range of 80–180 mg/dl seems reasonable in recommended. postoperative period. 10. Reduction of ICP in patients with head injuries can 13. Patients may present with head injuries in isolation be accomplished effectively using osmotic diuretics. or in conjunction with other injuries. Up to 50% of a. Mannitol is the most commonly used agent (0.25 to patients with severe traumatic brain injury have 1 g/kg) and is available for IV administration in major extra cranial injuries. As a result the presence either a 20% or 25% solution. With repeated doses of coexisting injuries should be actively sought and one must be cautious that serum osmolarity should excluded. A systematic approach to evaluation not be allowed to exceed 320 mOsm. Intravascular and initial management, such as that proposed volume depletion should be avoided. by Advanced Trauma Support, should be b. In patients with severe TBI and elevated ICP adopted for these patients. refractory to mannitol treatment, 7.5% hypertonic 14. Prophylactic hypothermia is of no use unless it is saline administered as second tier therapy can maintained for more than 48 hrs (decreases increase cerebral oxygenation and improve cerebral mortality). and systemic hemodynamics. 15. High dose methyl prednisolone is of no use in c. Hyperventilation is an effective way to reduce ICP. moderate to severe TBI, rather it increases mortality. It is useful in the setting of an acutely increased ICP that needs to be controlled until more definitive therapy can be initiated.

Fig. 1: Anesthetic management: The major goals of anesthetic management of TBI include

Indian Journal of Clinical Anaesthesia, July-September, 2018;5(3):299-305 304 Lalit Gupta et al. Anesthesia for neurosurgery (Part II)

Patients with TBI requiring surgery can be 11. Mahmood Ghazanwy, Rajkalyan Chakrabarti, Anurag subdivided into those who require emergent surgery and Tewari, Ashish Sinha. Saudi J Anaesth. 2014;8(4):529– those who require non-emergent surgery. 39. 12. Attari M, Salimi S. Awake craniotomy for tumor Emergent Surgery: These patients are already resection. Advanced Biomedical Research. 2013;2:63. intubated in area. Their neurologic condition 13. Curry P, Viernes D, Sharma D. Perioperative can be determined by GCS score, examining the pupils, management of traumatic brain injury. International and reviewing the CT scan. Journal of Critical Illness and Injury . 2011;1:27- 1. The patient’s hemodynamic status is also extremely 35. doi:10.4103/2229-5151.79279. 14. Crosby ET. in adults after cervical important. Patients may demonstrate a Cushing’s spine trauma. . 2006;104:1293–318. response (hypertension and bradycardia), which 15. Judith Dinsmore; Traumatic brain injury: an evidence- signifies brain stem compression from increased based review of management, Continuing Education in ICP. These classic findings may be masked by Anaesthesia Critical Care & Pain. 2013;13(6):189–95. hypovolemia, and their absence does not rule out 16. Jeremitsky E, Omert LA, Dunham CM, Wilberger J, brain stem compression. Rodriguez A. The impact of hyperglycemia on patients with severe brain injury. J Trauma. 2005;58:47–50. 2. These patients usually do not have ICP monitors in 17. Dumont TM, Visioni AJ, Rughani AI, Tranmer BI, place, but one can assume the presence of Crookes B. Inappropriate prehospital ventilation in severe intracranial hypertension. The presence of midline traumatic brain injury increases in-hospital mortality. J shift on CT scan and pupillary abnormalities on Neurotrauma. 2010;27:1233–41. reinforce this diagnosis. 18. Pasternak JJ, Lanier WL. Neuroanesthesiology update. J 3. Moderate hyperventilation should be used in these Neurosurg Anesthesiol. 2014;26(2):109-54.

patients until the dura is opened because the elevation in ICP is likely more detrimental than How to cite this article: Gupta L, Gupta B. short-term hyperventilation. Anesthesia for neurosurgery (Part II). Indian J 4. Blood pressure management is critical in these Clin Anaesth. 2018;5(3):299-305. patients. Non-emergent Surgery: Patients with TBI frequently have other injuries, especially fractures requiring operative fixation. The timing of surgery in these patients remains a controversial issue. In the setting of refractory elevations in ICP or very labile ICP, only emergent surgery should be performed.

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